By FRANCES LAMBERTS
“When the lakes run dry” was the headline of an article in New Scientist in March last year. The month before that, February 2016, had been the warmest since 1880, according to NASA temperature records. The extraordinary February warmth had eclipsed even the previous high-temperature anomaly, in January 2016.
The world over, under changing climate, freshwater bodies are warming and shrinking. The largest lake in southeast Australia has lost two-thirds of its volume since droughts in 2007-2009 and several others have shrunk significantly.
On the central plateau in Turkey, half of its lakes’ surface areas was lost between 2003 and 2013, one has dried up completely. Bolivia’s largest freshwater body, Lake Titicaca, “is heading towards trouble” and its second largest has become a salt pan; as drinking water source, it “is no more.”
At 2,700 square kilometers, that vanished Bolivian lake (Poopo) was more than a hundred times the size of Lake Watauga at full pool in summertime.
As climate change continues, freshwater lakes’ warming accompanies the global temperature rise. Per decade they have warmed an average of 0.34 degrees Celsius, since 1985. In the Arctic, where the temperature rise has been most rapid and formerly permafrost soils are thawing, nearly a fifth of all summertime ponds have vanished over the last 60 years.
In Alaska, shrinkage and loss of lakes will be “bad news for fish like salmon,” scientists studying that region predict, and for the migratory birds who depend on these lakes.
At lower latitudes, food production will be at risk as more evaporation due to warming, and more withdrawal for irrigation due to drying soils diminish the available water sources.
As the article summarizes, the smaller water volumes also concentrate nutrients and other land runoff, harming aquatic life and making the affected regions “less viable for agriculture.”
Closer to home than Turkey, Australia and Bolivia, the long California drought and Tennessee’s three droughts since the turn of the century should make us value more strongly and manage more wisely our own water resources.
As The Tennessean reported in January, in the historic, emergency-level drought in 2007, and in 2000-2001 and again last year, severe-drought conditions afflicted most of our state–more than 90% as shown in a graph in the article. (In November and early December 2016, 99% of the state was under severe drought.)
The succession of droughts in so short a time span has left water-utility managers “trying to plan for a worst-case scenario and “searching for backup water supplies [for] the next time we have a drought.”
Instead of securing the potential back-up sources–wetlands and small streams that drain into larger ones– the administration is rolling back federal clean-water protections.
In late February President Trump, stating that protection should be limited to “navigable waters affecting interstate commerce,” signed an executive order to rescind the WOTUS rule (Waters of the United States).
Especially under continuing global warming, his action puts at considerable risk the health and future adequacy of water systems, in Tennessee and across the land.